Significant reduction of line downtime

The targeted automation of manual testing processes creates new freedom

Quality and time are crucial factors in the optimization of manufacturing processes. Ensuring the high quality standard in production while at the same time saving a significant amount of time ultimately ensures your own competitiveness. Test systems to ensure high product quality play a decisive role. Systems that are to be used to automate manual testing processes must meet very special requirements.

appeared in the EPP 08/2013

As a manufacturer of high-tech products in the field of micro and power electronics, Sensor-Technik Wiedemann GmbH from Kaufbeuren (STW) offers a wide range of products for a wide range of applications in the automotive industry, mechanical engineering, plant engineering, medical technology and the food industry. These include the development and production of freely programmable electronic controls for mobile machines.

Automation of manual testing processes

At the beginning of 2012, STW was looking for an effective system to minimize the time of initial sample, small batch, prototype and setup checks, thereby gaining valuable production time. With 8-20 product changes per day, the initial sample inspection and set-up control is an integral part of the high quality standard. Manual optical inspection solutions (MOI) already established in the system process are often faulty, inflexible, incomprehensible and simply too slow. Automatic Optical Inspection (AOI), however, was out of the question for this application due to the high initial cost and long programming times.

The aim was to have a system that would assist the operator with controls in all respects, but still allow people's judgment to react flexibly to unforeseen problems. Following a test phase of several systems that were of interest to STW, the industry solution EFA Inspection from LEBERT Software Engineering (LSE for short) was able to prevail. In October 2012, the new system was integrated into the ongoing process.

Flexible and easy programming

EFA Inspection is a semi-AOI solution based on conventional hardware - without the need for expensive or special hardware. This system closes the gap between automatic and manual optical inspection. In contrast to the AOI, the system also compares, for example, the assembly plan with the assembled printed circuit board by the operator. Possible deviations of the documents can be adapted immediately before they are handed over to the current production company. All information (assembly plan, coordinates, item number, part designation, values, etc.) required by the operator on the SMD line is read into EFA Inspection. The programming effort for an EFA program is usually only a few minutes. The data can be integrated in almost any format (EFA understands more than 200 different image and data formats). Also, the joining of up to three different lists (coordinate data, BOM information, own part number lists, ...) is done with just a few clicks.

The creation of the EFA program can be prepared anywhere. In addition, it can be used again during a restart - the creation is therefore only required once. This saves valuable process time.

The operator on the line only has to call up the corresponding program and create a current recording of the printed circuit board to be tested.

High-quality images provide a reliable basis for evaluation

To create a high-quality image of the assembled printed circuit board, it is inserted into the EFA Picture Touch High Resolution System. The illumination of the system can be optimally adjusted per printed circuit board and makes self-lasered component labels visible. A camera is used to create several partial recordings per board, which are then assembled to a high-quality overall recording. The lighting and the camera are operated completely via the touch screen computer of the EFA Picture Touch HR system.

Fast and traceable inspection

The image of the current printed circuit board is now read into the associated EFA program. Together with the assembly plan and the component information, all the information required for the corresponding assembly position can be seen at a glance. So that no component or article can be overlooked, the inspection process is program-controlled. EFA Inspection automatically displays one part after the other centered in all windows for an initial sample inspection, eliminating the need to search or manually invoke it. Depending on the setting, the inspector will see each item individually or only one item per item number. The current image of the component can be compared both with the assembly plan and at the same time with previous inspections (Golden Board). For a small series inspection with a golden board comparison, the recordings can also be checked in sections. EFA Inspection offers up to 7 different types of inspection.

The evaluation ("GOOD", "UNSAFE" "FAIL") of the individual positions is carried out by the operator via a specially programmed keyboard. In the case of an error or in case of uncertainties, predefined or freely editable justifications can be submitted. For each component, the corresponding rating, the name of the examiner and a time stamp are logged. The entire inspection process can be traced at any time via this complete logging.

Process reliability gained

In the past, two people at STW were busy controlling the initial sample or set-up control of a module via a time-consuming process. Since the introduction of EFA Inspection, only one person is needed, as all information is visible at a glance. With this system, STW has been shown to reduce the time spent on revisions and initial sample inspections by up to 80%. The production has not only gained valuable production time, but also secures the quality of the products through a predefined process.

EFA Inspection is part of the EFA SmartSuite, an in-process LSE solution that supports the entire manufacturing process from pre-production to final inspection through dedicated applications. EFA SmartSuite is a "living" system, which has emerged directly from a wide range of customer requirements and is regularly expanded with new solutions.

"The customer gives us the direction so that software can be created for the customer," says Mr. Lebert, Managing Director of LSE.

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